U.S. patent application number 17/420695 was filed with the patent office on 2022-03-31 for sandwich panel for a car able to carry a load.
This patent application is currently assigned to Autoneum Management AG. The applicant listed for this patent is Autoneum Management AG. Invention is credited to Mathias KOSSANYI.
Application Number | 20220097341 17/420695 |
Document ID | / |
Family ID | |
Filed Date | 2022-03-31 |
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United States Patent
Application |
20220097341 |
Kind Code |
A1 |
KOSSANYI; Mathias |
March 31, 2022 |
SANDWICH PANEL FOR A CAR ABLE TO CARRY A LOAD
Abstract
Sandwich panel for use in a vehicle comprising at least a core
layer and two fibrous layers in contact with and firmly connected
to the core layer, both sides being impregnated with polyurethane
whereby the polyurethane is embedding the fibers and binding to the
board material, and whereby the sandwich panel further comprises at
least a polyether polyurethane foam layer fully impregnated with
polyurethane and in contact and firmly connected to the outer
surface of at least one fibrous layer by the polyurethane, and a
skin layer on the outer surface of the polyether polyurethane foam
not in contact with the fibrous layer consisting of compressed
polyurethane.
Inventors: |
KOSSANYI; Mathias; (Paris,
FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Autoneum Management AG |
Winterthur |
|
CH |
|
|
Assignee: |
Autoneum Management AG
Winterthur
CH
|
Appl. No.: |
17/420695 |
Filed: |
January 9, 2020 |
PCT Filed: |
January 9, 2020 |
PCT NO: |
PCT/EP2020/050388 |
371 Date: |
July 5, 2021 |
International
Class: |
B32B 5/26 20060101
B32B005/26; B32B 5/02 20060101 B32B005/02; B32B 5/18 20060101
B32B005/18; B32B 5/24 20060101 B32B005/24; B32B 15/14 20060101
B32B015/14; B32B 27/06 20060101 B32B027/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 16, 2019 |
EP |
19152040.2 |
Claims
1. A sandwich panel for use in a vehicle comprising at least a core
layer covered on both sides with a fibrous layer to form a
sandwich, both sides being impregnated with polyurethane whereby
the polyurethane is embedding the fibers and binding to the core
material, characterized in that the sandwich panel further
comprises: at least a resilient slab foam layer based on polyether
polyurethane fully penetrated and engulfed with polyurethane and in
contact and firmly connected to the outer surface of at least one
fibrous layer by the polyurethane; a skin layer on the outer
surface of the polyether polyurethane foam not in contact with the
fibrous layer consisting of compressed polyurethane; and whereby
the polyurethane bulge inside the core layer to bind the adjacent
layer to the core layer without fully filling the core layer
structure.
2. The sandwich panel according to claim 1 whereby the polyether
polyurethane foam layer is having a surface weight of between 48 to
240 gsm or between 72 and 192 gsm.
3. The sandwich panel according to claim 1, whereby the
polyurethane foam used for impregnation is based on polyester or
polyether polyol.
4. The sandwich panel according to claim 1, whereby the
polyurethane used for impregnation has an area weight of between
200 and 2000 gsm per surface impregnated.
5. The sandwich panel according to claim 1, whereby the first and
second fibrous mat can be made up of the same or different fibers,
fiber mixtures, or fibrous layers.
6. The sandwich panel according to claim 1, whereby the first and
or second fibrous mat comprises at least one of inorganic fibers,
synthetic fibers, polyolefin, organic regenerated fibers, natural
fibers, animal fibers, and a mixture of one or more thereof.
7. The sandwich panel according to claim 1, whereby the first and
or second fibrous mat has an area weight of between 100 and 900
gsm.
8. The sandwich panel according to claim 1, whereby the core layer
is a spacer board with a honeycomb, corrugated or tubular grit
structure, or a closed cell foam structure.
9. The sandwich panel according to claim 1, whereby the core
material is made from plastic, a natural material, an inorganic
material, a combination of natural fibers and a resin, or a
metal.
10. The sandwich panel according to claim 1, whereby the core layer
is a honeycomb board with a cell diameter of between 4 and 10 mm or
preferably between 6 and 8 mm.
11. The sandwich panel according to one of claim 1, whereby the
core material is polyester closed cell foam board with a density of
between 60 and 200 kg/m3.
12. The sandwich panel according to claim 1, whereby the thickness
of the core layer is between 2 and 30 mm or 5 and 20 mm.
13. The sandwich panel according to claim 1, further comprising at
least on one surface of the panel raised protrusions in the skin
layer formed, like a raised pattern in the form of knobs, waves or
embellishments, surface patterning similar to wood or leather
graining, stiffening ribs, or beams.
14. The sandwich panel according to claim 1, further comprising
additional layers laminated to at least one surface fully or
locally, chosen from a tufted carpet, a nonwoven carpet, knitted
layer, foil layer, foamed, spray or RIM skin layer, a foil, a film,
a scrim layer, a logo, or anti-sliding pad.
15. The sandwich panel according to claim 1, further comprising an
in-mold coating of at least one surface skin layer fully or
partially covering the surface comprising one of an aesthetic
coating, a coating impervious to water and/or grease, a thermal
conductive coating, an electro conductive coating, or
electro-magnetic shielding coating.
16. A process for the production of the sandwich panel according to
claim 1: wetting a sandwich stack comprising at least one core
layer and two fibrous layers in contact with the surfaces of the
core layer on both sides with a polyurethane forming mixture which
includes a foam stabilizer; placing the wetted sandwich stack in a
compression mold; closing the mold and maintaining the mold at a
temperature in the range between 40.degree. and 200.degree. C. to
mold the part and to harden the polyurethane foam forming mixture
and thereby forming a molded part, whereby the polyurethane is
embedding the fibers and binding to the core layer; removing the
molded article from the mold, characterized in that the sandwich
stack further comprises at least a polyether polyurethane slab foam
layer covering the outer surface of a fibrous layer, and whereby on
that side the polyurethane mixture is applied on top of the
polyether polyurethane foam surface and the polyurethane penetrates
the slab foam layer as well as the fibrous layer and binding to the
core layer, and whereby during the compression of the stack in the
close mold a polyurethane skin is formed on top of the polyether
polyurethane foam surface not in contact with the fibrous
layer.
17. A method of using of the sandwich panel according to claim 1 as
a load floor panel, a main floor panel for a passenger compartment,
as roof module, bonnet, tailgate module, door module, floor panel
module, parcel shelf, spare wheel cover, interior trim component,
as a battery or battery pack cover, as a computer or battery box,
or as a partitioning panel.
18. The sandwich panel according to claim 6, wherein the inorganic
fibers comprise glass, carbon, basalt or aramid fibers; wherein the
synthetic fibers comprise polyester; wherein polyolefin comprises
polyethylene, polypropylene, or polyamide fibers; wherein the
organic regenerated fibers comprise viscose, rayon, or modal
fibers; wherein the natural fibers comprise hemp, flax, kenaf,
bamboo or other cellulose fibers; and wherein the animal fibers
comprise wool fibers.
19. The sandwich panel according to claim 9, wherein the plastic
comprises polyethylene terephthalate (PET), polybutylene
terephthalate (PBT), polyamide, polypropylene, polyethylene, a
polylactic based material, Polyether ether ketone (PEEK),
polycarbonate; wherein the natural material is paper or cardboard;
wherein the inorganic material comprises an aramid.
Description
[0001] This application is a national stage application under 35
U.S.C. 371 and claims the benefit of PCT Application No.
PCT/EP2020/050388 having an international filing date of Jan. 9,
2020, which designated the United States, which PCT application
claimed the benefit of European Patent Application No. 19152040.2
filed Jan. 16, 2019, the disclosure of each of which are
incorporated by reference herein.
TECHNICAL FIELD
[0002] The invention is directed to a sandwich panel for cars able
to carry a load, like battery electric vehicles, personal cars or
small transport vans, a method of producing such a part and the use
of such a panel in a car.
BACKGROUND ART
[0003] Personal cars and small transport vehicles may have a trunk
or comparable area where goods can be loaded and transported. The
flooring panel used in such area must be able to carry high loads.
Conventionally these panels are produced as sandwiched panels with
a stiff core and skin layers to enhance the bending stiffness.
[0004] The three-layer sandwich construction is preferred for use
in automotive lightweight engineering where flat and shell-shaped
panels are required to withstand high bending loads. In this
construction the upper and lower facings are made up of a fiber
reinforced composite which is responsible for the flexural strength
of the compound and is capable of withstanding the pressure and
tensile stresses that arise. The fibers act as a reinforcing
component and are connected to each other by means of a fabric
construction or a bonded web.
[0005] Polyurethane (PU) is often used for fixing the glass fiber
mat which, because of its controllable foaming properties, also
benefits lightweight construction. The PU matrix, in addition to
fixing the glass mat, may be at the same time responsible for
binding the honeycomb core to the facings in a sandwich
construction.
[0006] An example of such a sandwich load floor panel according to
the state of the art, as for instance disclosed in EP1609576, is
having a cardboard honeycomb core and glass fiber mat skins,
whereby the core and glass mats are combined by impregnation with a
reactive polyurethane mixture. The polyurethane wetted layers are
placed in a mold and compression molded into the required shape.
During this molding step the polyurethane reacts by forming foam
thereby increasing the pressure inside the closed mold. The
impregnated foam binds the layers together. This gives a sturdy
load floor, with a bad appearance. Although the fibers are embedded
in the foam they are still visible on the surface.
[0007] A big disadvantage of the current process is that the
pressure forces the polyurethane material inside the honeycomb
rather than filling surface embellishment or formed cavities within
the mold surface to give the desired surface appearance and
texture. Also the gas produced during the foaming process will form
bubble defects on the surface of the part produced. Obtaining a
good definition of surface features like ribs, designs in the form
of wood grain or leather embossments or beading on the surface of
the part is therefore not possible. Hence, in practice these load
floors are covered with an aesthetic layer like a carpet for the
used or visible surface, called A-surface, and left with a bad back
surface called B-surface.
[0008] In some cars it is foreseen to turn the load floor to the
B-surface if a load is carried that might damage or soak the A
surface, in particular for wet loads or loads with a likelihood of
liquid spilling. Although the glass fibers in the B-surface are
initially protected, harsh usage might damage the foam embedding,
for instance by scratches, and glass-fiber-ends might stick out of
the surface being a hazard, making the B-surface even worse.
[0009] Adding additional layers on the B-surface might give a
better appearance but will increase the weight of the final part as
well as increase the complexity of the production process.
[0010] It is the object of the invention to optimize the sandwich
panel of the state of the art, particularly to obtain a more
versatile light weight alternative to the current load floor as
well as the way to produce such a panel without the known drawbacks
as discussed.
SUMMARY OF INVENTION
[0011] This object is achieved by a sandwich panel with the
features of claim 1, by a method of producing such a panel with the
features of claim 16 and by the use of such a panel according to
claim 17.
[0012] In particularly by a Sandwich panel for use in a vehicle
comprising at least a core layer covered on both sides with a
fibrous layer (7) to form a sandwich, both sides being impregnated
with polyurethane whereby the polyurethane is embedding the fibers
and binding to the core material, characterized in that the
sandwich panel further comprises at least a resilient slab foam
layer based on polyether polyurethane fully penetrated and engulfed
with polyurethane and in contact and firmly connected to the outer
surface of at least one fibrous layer by the polyurethane, and a
skin layer on the outer surface of the polyether polyurethane foam
not in contact with the fibrous layer consisting of compressed
polyurethane and whereby the polyurethane bulge inside the core
layer to bind the adjacent layer to the core layer without fully
filling the core layer structure.
[0013] Surprisingly by using a polyether polyurethane resilient
foam layer on top of the fibrous layer before wetting with the
polyurethane foam mixture results in a good fixation of all layers
together reducing the amount of foam in the core layer structure
and increasing the surface definition. In addition, the scratch
resistance could be increased. The combination of high resilient
polyether polyurethane foam with a dense open cell structure seems
to work as a polyurethane foam guide or resistance for the foam
flow during the compression molding of the part. However, the
structure is initially open enough to obtain a good penetration of
the polyurethane foam through the polyether-polyurethane slab foam
layer and fibrous layer and on the contact surface between the core
layer and the fibrous layers ensuring an even binding of all
layers. In addition, the foam enables a better filling of the
surface structure in the mold, enhanced by the pressure and
temperature of the mold a thick scratch resistant and even skin
layer is formed on the part surface.
[0014] Preferably resilient polyurethane slab foam based on
polyether polyol is used. For instance, slab foam produced from a
polyether polyol and an isocyanate TD80, both might be optionally
modified. Additional additives like catalysts, stabilizers, dyes or
flame retardants might be added where deemed necessary. As a
catalyst an amine catalyst might be used.
[0015] Alternatively combustion modified conventional polyether
polyurethane foam might be used, for instance a flexible polyether
polyurethane foam as promoted by Recticel.RTM.. These foams are
normally used in the upholstery and furniture market and less known
in the automotive field of trim parts and cladding structures.
[0016] Preferably, the polyether polyurethane foam has a net
density of between 20 to 26 kg/m3.
[0017] Preferably, the polyether polyurethane foam layer is having
a surface weight of between 48 to 240 gsm, preferably between 72
and 192 gsm.
[0018] Surprisingly, already a thin layer of the
polyether-polyurethane foam, with a thickness of between 2 to 10
mm, preferably between 3 to 5 mm is enough to obtain the desired
effect of having a better polyurethane wetting and impregnation
distribution flow over the covering layers of the sandwich stack
and inside the 3D surface features.
[0019] Preferably the foam is resilient and has a 40% compression
resistance of between 5.0-6.5 kPa as measured with ISO3386.
[0020] The impregnation of the polyether-polyurethane slab foam and
underlying fibrous layer is obtained by wetting the layers with a
polyurethane mixture; this is preferably achieved by spraying of
the mixture. Either the spray head or the part to be wetted can be
moved to obtain an even spreading of the mixture. Preferably higher
amounts of mixture can be applied locally to strengthen areas or in
areas with an increased thickness and or increased 3D definition or
requirement.
[0021] To obtain a strong sandwich both sides of the sandwich stack
are wetted.
[0022] As a wetting polyurethane mixture a mixture of polyol and
isocyanate can be used that is premixed just before application.
Preferably, it enfolds its full foam potential when the wetted
layers are placed in the heated tool such that the pressure of the
closed tool and the temperature together enables an even
distribution throughout all layers and into the surface
details.
[0023] The polyurethane forming mixture generally used in the
process of the present invention will generally include: [0024] at
least one polyol component with an average OH number of 300 to 700
which includes at least one short chain and one long chain polyol,
the individual polyols having a functionality of 2 to 6; [0025] at
least one isocyanate; [0026] optionally a blowing agent; [0027] an
activator; [0028] optionally auxiliary substances, mould release
agent and additives.
[0029] Suitable polyols can be polyester or polyether based.
[0030] U.S. Pat. No. 808,485 discloses preferred mixtures for
wetting the polyether and fibrous layers comprising an isocyanate
component and a polyol component comprising one or more natural oil
based polyols, which might be used with the invention according to
this application.
[0031] Preferably, the polyurethane foam used for wetting has an
area weight of between 200 and 2000 gsm. In case one surface is
covered with a carpet or other layer different amounts for the
wetting of the A- and B-surface might be used, for example 600 gsm
for the A-surface with the carpet and 1400 gsm for the B-surface
with the embellishments.
[0032] Preferably, the reaction speed is optimal at a temperature
of 130.degree. C. The temperature condition of the mold is adapted
accordingly.
[0033] Preferably, a first and second fibrous mat is used to cover
both sides of the core structure and function as reinforcing
layers. The first and second fibrous mat is preferably the same
however can be made up of different fibers, fiber mixtures or
fibrous layers.
[0034] Preferably the first and or second fibrous mat comprises at
least one of inorganic fibers, for instance glass, carbon, basalt
or aramid fibers, synthetic fibers such as for instance polyester,
polyolefin for instance polyethylene or polypropylene, or polyamide
fibers, organic regenerated fibers, for instance viscose, rayon, or
modal fibers, natural fibers such as for instance hemp, flax,
kenaf, bamboo or other cellulose fibers, animal fibers such as for
instance wool fibers or any possible mixture with these fibers. The
fibers can be from virgin, recycled or reclaimed origin.
[0035] Preferably a glass fiber mat or a mat comprising glass
fibers is used as this increases the bending stiffness.
[0036] With fibers both endless filaments and cut filaments forming
staple fibers are meant to be within the scope of the current
invention.
[0037] The mat preferably has an area weight of between 100 and 900
gsm without the foam impregnation.
[0038] Preferably, the core layer is a spacer board with a
honeycomb, corrugated or tubular grit structure or a closed cell
foam structure.
[0039] The thickness of the core layer is between 2 and 30 mm,
preferably between 5 and 20 mm, preferably the thickness is
variable.
[0040] As a preferred core layer a board type material may be used
that provides a bi-directional support, preferably having open
cells mainly in the thickness direction of the plate, for instance
tubular, corrugated or honeycomb type boards.
[0041] Preferably the core layer is made from plastic, for instance
one of polyester, like polyethylene terephthalate (PET) or
polybutylene terephthalate (PBT), polyamide, or a polyolefin type,
like polypropylene or polyethylene, a polylactic based material,
Polyether ether ketone (PEEK), polycarbonate or a natural material
like paper or cardboard or from an inorganic material like for
instance aramid or from combination of natural fibers and a resin
or a metal like for instance aluminum.
[0042] The starting material might be folded in an expandable form
to reduce storage before production. Hence the folded form is
expanded and set before the production of the automotive part.
[0043] A cardboard honeycomb is preferred as this is foldable,
light weight and cost effective. The cardboard must be strong
enough to withstand the pressure during production. Preferably a
paper weight of between 70 and 140 gsm is used.
[0044] Preferably the honeycomb used has cells with a diameter
between 4 and 10 mm, preferably between 6 and 8 mm. The cell
diameter may be decided on based on the final load requirements,
the scratch resistance and 3D design of the top surface and may
vary with paper weight and board thickness used.
[0045] Decreasing the cell diameter of the honeycomb will result in
a more stable and stiff part. Surprisingly also the 3D definition
of the surface as well as the scratch performance is enhanced, as
the polyurethane foam is more compressed and the skin becomes
denser.
[0046] Alternatively a polyester, polypropylene, polyethylene or
aramid honeycomb with similar dimensions may be used.
[0047] In a preferred solution, stiff closed cell foam preferably
polyester closed cell foam is used as the core layer.
[0048] The impervious polyester foam core layer has a compression
modulus, measured according to ISO 844, of at least about 30 MPa,
preferable minimum of 55 MPa.
[0049] Polyester foam according to the invention as claimed is
based on thermoplastic polyester resin and preferably made of a
foam-able grade of semi crystalline polyethylene terephthalate
(PET). As they are melt extruded with a suitable chemical or
physical blowing agent, these thermoplastic polyester resins yield
closed-cell foams. The foam can be produced by recycled polyester
or virgin raw material or a combination of both. Within the scope
of the present invention polyester, in particularly polyethylene
terephthalate, foam as core layer is not including polyester based
polyurethane (PUR) foam.
[0050] The closed cell PET foam layer has a density of 60 to 200
Kg/m3, preferably 75 to 120 Kg/m3.
[0051] After molding additional layers might be laminated on at
least one surface, for instance one chosen from a tufted carpet, a
nonwoven carpet, knitted layer, foil layer, foamed, spray or RIM
skin layer, a foil, a film or a scrim layer. Also cameos can be
laminated only locally like patches or logos to further enhance
aesthetics or function, like anti sliding pads.
[0052] Carpet or other textile surface coverage might be glued or
laminated to recesses in the side of the panel to obtain a flush
and nice finish of the part.
[0053] Preferably an additional surface layer is added to at least
one of the surfaces, fully or partially covering that surface using
in mold coating. Examples of such in mold coating can be local
logos or text, or technical coatings for instance to render the
part impervious to water or grease, to obtain a thermal conductive,
electro conductive or electro-magnetic shielding layer on at least
one of the surfaces.
[0054] Preferably a reversible panel is created with at one surface
a carpet type layer and on the other surface a surface according to
the invention with optionally a surface pattern, ribbing or a
raised rim to further enhance the functionality of the that layer.
Also drainage holes or guiding ribs might be integrated to drain
spilled liquid in case the panel is used as a horizontal load
bearing board for instance a floor board, load floor or battery
cover.
[0055] Further features might be incorporated in the panel,
directly during the compression molding or after the compression
molding, for instance clips, mounting appliances, handles, nuts,
brackets or reinforcement bars etc. These appliances are preferably
made of polyamide or polyester, metal. Optionally carbon or glass
fiber reinforced materials might be used.
[0056] A process for the production of the sandwich panel according
to the invention comprising: [0057] wetting a sandwich stack
comprising at least one core layer and two fibrous layers in
contact with the surfaces of the core layer on both sides with a
polyurethane forming mixture which includes a foam stabilizer;
[0058] placing the wetted sandwich stack in a compression mold
[0059] closing the mold and maintaining the mold at a temperature
in the range between 40.degree. and 200.degree. C. to mold the part
and to harden the polyurethane foam forming mixture and thereby
forming a molded part, whereby the polyurethane is embedding the
fibers and binding to the core layer; removing the molded article
from the mold, characterized in that the sandwich stack further
comprises at least a polyether slab foam layer covering the outer
surface of a fibrous layer and whereby on that side the
polyurethane mixture is applied on top of the polyether
polyurethane foam surface and the polyurethane is penetrating the
slab foam layer as well as the fibrous layer and binding to the
core layer and whereby during the compression of the stack in the
close mold a polyurethane skin is formed on top of the polyether
polyurethane foam surface not in contact with the fibrous
layer.
[0060] The process might further include the step of in mold
coating an additional layer on top of the skin layer.
[0061] The process might further include the step of laminating
additional layers on the skin layer after the thermo compression
molding step, advantageously the rest heat available in the part is
used to enable an easy laminating step.
[0062] Also normal cutting and finishing steps might be added to
the process where necessary.
[0063] Use of the floor panel according to the invention as a load
floor panel, a main floor panel for a passenger compartment, as
roof module, bonnet, tailgate module, door module, floor panel
module, parcel shelf, spare wheel cover, interior trim component,
as a battery or battery pack cover, as a computer or battery box or
as a partitioning panel.
BRIEF DESCRIPTION OF DRAWINGS
[0064] FIG. 1 Schematic figure of a car with an example of a part
that can be produced according to the invention.
[0065] FIGS. 2 and 3 Schematic layout of the material layers in the
final product.
[0066] FIG. 4 schema of the production of a part according to the
invention.
DETAILED DESCRIPTION
[0067] FIG. 1 shows partially a personal vehicle back area 20, with
a load floor that might be produced according to the invention. The
load floor can be designed with at least one surface according to
the invention, preferably with both surfaces according to the
invention. Preferably the load floor is designed such that it can
be reversed between an A side and a B side, being the opposite
surfaces on the load floor panel, whereby one side might be
equipped with a carpet type surface for instance a tufted carpet or
a nonwoven carpet and the other side might have a bare surface
according to the invention.
[0068] FIGS. 2 and 3 are showing example cross sections of sandwich
panels (1) according to the invention with a honeycomb core layer
(2) with chambers 3 which form open channels between both surfaces
of the core layer. The walls of the channels can be formed from
different materials such as but not limited to paper, cardboard or
plastics material like polyolefin, polypropylene, polyethylene or
polyester based materials as well as composite materials made of
natural fibers and thermoplastics.
[0069] Although the core layer depicted is a honeycomb other grid
forms might be used such as tubular, corrugated or closed cell
foam.
[0070] The core material is preferably covered on both sides with a
fibrous reinforcement layer (7) to form a sandwich, although the
covering layers between the sides might vary, they must be even in
their tensile strength performance under thermal conditions to
prevent warping of the part.
[0071] At least on one side coverage (4) might consist of at least
a fibrous reinforcement layer (7) and a resilient polyether slab
foam layer (6) which are penetrated and engulfed by polyurethane
foam. The polyurethane foam will form a skin layer (5) on top of
the polyether polyurethane foam layer, be pressed inside the
polyether polyurethane foam layer and inside the fibrous layer and
a small amount will finally bulge inside the top of the open
channels of the honeycomb core material (8), by doing so it will
also bind the core layer and the other layers together. Due to the
forming in a compression mold the coverage structure is compressed
to form a dense skin and an overall strong structural layer.
[0072] The thus bound layers form together a strong sandwich that
can bear high loads on its surface without bending or sagging
substantially.
[0073] The construction of FIG. 2 can be used in many different
applications and due to the use of the polyether polyurethane foam
on one or both sides it is possible to use the board without any
covering layer. The fibrous structure of the fibrous mats
particularly when they are glass fiber mats is no longer visible
and possible damaging of the surface will no longer free the fiber
content.
[0074] Part of the use of the board as load floor or flooring panel
in the passenger compartment, it can now also be used as a floor
panel in a frunk--a front storage space in an electric vehicle.
[0075] It is also possible to use the panel as a battery cover or
computer panel or box, as the material is very light in weight but
has a high stiffness and impact protection. If needed the panel can
be locally further enforced with metal beams or plates to further
enhance the crash protection. It is also possible to introduce
crash break lines within the core to enable crash zones if
needed.
[0076] FIG. 3 also shows a preferred example of a panel according
to the invention build up as a reversed load floor, for instance
like depicted in FIG. 1. The main layout and numbering is the same
as in FIG. 2. However here the reversible load floor has an
A-Surface (A) and a B-surface (B) both surfaces good enough to form
an A quality surface but with different functions.
[0077] The A-surface in this case is the classical carpet surface
with a tufted carpet (17) laminated on the molded part.
[0078] The B-surface is now formed by the dense polyurethane skin
whereby the surface contains embellishments in the form of a raised
pattern on the surface of the part with knobs (14) and ribs (15)
mainly filled by the polyurethane skin material. In addition the
surface contains a raised rim (16) at the edge of the part whereby
the raised rim is mainly formed by the polyether polyurethane foam
layer (6 not to scale) that rebounds pushing the polyurethane foam
(5 and 5') back into the recess in the mold, in addition the foam
further fills the space forming a dense foam (5') and even denser
skin (5) on the foam resulting in a durable rim.
[0079] FIG. 4 is schematically showing the main steps in a
preferred production process for the sandwich panel according to
the invention with step
[0080] Wetting of the material layers with the polyurethane mixture
on both sides (100) in particular by putting the materials 1 in
order underneath or opposite one or more polyurethane spray heads
12 that can move in relation to the surface to be covered. The
polyurethane may be mixed and dosed immediately before spraying for
instance using a first dosing system for the isocyanate (9) and a
second dosing system for the polyol (10) into a mixing unit 11.
Additives might be added to the stock or directly to the mixing
unit;
[0081] Transferring the thus wetted material stack inside a heated
mold (200) with a first and second mold half 13a and b, that can be
closed together to form the final part;
[0082] Thermo-compression molding the part (300) by closing the
mold and keeping it closed under pressure. The heat of the mold
will (further) activate the polyurethane mixture creating a foam
pressure that will help spreading the mixture through the layers as
well as forming a skin on the surface of the part;
[0083] Unmolding the part (400).
[0084] After the unmolding additional surface layers like a carpet
layer can be put on top of at least one surface to form a surface
with a nice soft surface. For instance a tufted or nonwoven carpet
layer or a fabric, like a neoprene fabric might be used. Preferably
a small recess is made in the panel to obtain a plain level with
the top of the carpet surface when positioned.
[0085] As an additional step also other appliances can be attached
to the part like for instance handles, hinges etc. depending on the
part and function.
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